/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.library.dprofile;

import org.apache.iotdb.commons.udf.utils.UDFDataTypeTransformer;
import org.apache.iotdb.library.util.Util;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;

/**
 * calculate the approximate percentile
 */
public class UDAFQuantile implements UDTF {
    private org.apache.iotdb.library.dprofile.util.HeapLongKLLSketch sketch;
    private double rank;
    private TSDataType dataType;

    @Override
    public void validate(UDFParameterValidator validator) throws Exception {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.INT32, Type.INT64, Type.FLOAT, Type.DOUBLE)
                .validate(
                        K -> (int) K >= 100,
                        "Size K has to be greater or equal than 100.",
                        validator.getParameters().getIntOrDefault("K", 800))
                .validate(
                        rank -> (double) rank > 0 && (double) rank <= 1,
                        "rank has to be greater than 0 and less than or equal to 1.",
                        validator.getParameters().getDoubleOrDefault("rank", 0.5));
    }

    @Override
    public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
            throws Exception {
        configurations
                .setAccessStrategy(new RowByRowAccessStrategy())
                .setOutputDataType(parameters.getDataType(0));
        dataType = UDFDataTypeTransformer.transformToTsDataType(parameters.getDataType(0));
        int K = parameters.getIntOrDefault("K", 800);
        rank = parameters.getDoubleOrDefault("rank", 0.5);

        sketch = new org.apache.iotdb.library.dprofile.util.HeapLongKLLSketch(K * 8);
    }

    @Override
    public void transform(Row row, PointCollector collector) throws Exception {
        double res = Util.getValueAsDouble(row);
        sketch.update(dataToLong(res));
    }

    @Override
    public void terminate(PointCollector collector) throws Exception {
        long result = sketch.findMinValueWithRank((long) (rank * sketch.getN()));
        double res = longToResult(result);
        switch (dataType) {
            case INT32:
                collector.putInt(0, (int) res);
                break;
            case INT64:
                collector.putLong(0, (long) res);
                break;
            case FLOAT:
                collector.putFloat(0, (float) res);
                break;
            case DOUBLE:
                collector.putDouble(0, res);
        }
    }

    private long dataToLong(Object data) {
        long result;
        switch (dataType) {
            case INT32:
                return (int) data;
            case FLOAT:
                result = Float.floatToIntBits((float) data);
                return (float) data >= 0f ? result : result ^ Long.MAX_VALUE;
            case INT64:
                return (long) data;
            case DOUBLE:
                result = Double.doubleToLongBits((double) data);
                return (double) data >= 0d ? result : result ^ Long.MAX_VALUE;
            default:
                return (long) data;
        }
    }

    private double longToResult(long result) {
        switch (dataType) {
            case INT32:
                return (double) (result);
            case FLOAT:
                result = (result >>> 31) == 0 ? result : result ^ Long.MAX_VALUE;
                return Float.intBitsToFloat((int) (result));
            case INT64:
                return (double) (result);
            case DOUBLE:
                result = (result >>> 63) == 0 ? result : result ^ Long.MAX_VALUE;
                return Double.longBitsToDouble(result);
            default:
                return (double) (result);
        }
    }
}
